The “Reef” Behind the Reef: Making Sense of the Great Barrier Reef’s Mysterious Green Donuts

In person talk
Thursday 9 November, 6pm: Dive into the mysteries of Great Barrier Reef's 'Halimeda Donuts' in this talk with Professor Jody Webster and learn a bit about their vital role in our iconic ecosystem.

On the outer shelf of Australia’s Great Barrier Reef (GBR), under 20–50 meters of water, lies a broad expanse of giant green “donuts”, each several hundred meters across. These bizarre features were constructed over numerous millennia by green calcareous algae from the Halimeda genus. The Halimeda “bioherms” on the northern Great Barrier Reef shelf are the most extensive, actively accumulating Halimeda deposits in the world, contributing to their Outstanding Universal Value to the GBR from a geological and geomorphological perspective. However, little is known about the fundamental processes that control Halimeda bioherm distribution and development, and their role as key inter-reef habitats and carbon sinks.

In August and September 2022, Professor Jody Webster led a multidisciplinary and international team of scientists on Australia’s RV Investigator to better understand these donut-shaped deep-water reefs by mapping and sampling them in breathtaking detail. The mission of Project HALO (Halimeda Bioherm Origins, Function and Fate) is to illuminate how the bioherms formed over the past 12,000 or so years (i.e., the Holocene) and their importance in biogeochemical nutrient cycling and as modern habitats amid one of Earth’s  most important but vulnerable ecosystems – the GBR. In this seminar, he will summarise some of the first voyage results and highlights, the exciting plans for post voyage scientific work, as well provide a few personal vignettes on what it's like to sail and lead a research voyage on the RV Investigator.

About the speaker

Marine geoscientist Jody Webster Co-Coordinator of the Geocoastal Research Group (GRG) at the University of Sydney. An expert in carbonate sedimentology and stratigraphy and interpretation of marine geology and geophysical data, he investigates coral reef evolution and associated environmental changes. Educated at the University of Sydney (Bsc Hons, PhD) he has worked at University of Papua New Guinea (UPNG) (2001-2), University of California (Santa Cruz) (2002-3), the Monterey Bay Aquarium Research Institute (MBARI) (2003-5), James Cook University (JCU) (2005-8) and now the University of Sydney where he was appointed Professor of Marine Geoscience (2021). He has served on many national and international committees associated with the International Ocean Discovery Program (IODP) (2009-present). Jody has led or participated in numerous blue-water research voyages, including as Co-chief Scientist on IODP Expedition 325 Great Barrier Reef Environmental Changes and the upcoming IODP Expedition 389 Hawaiian Drowned Reefs in Aug-Nov, 2023. 

Event details

In person talk.

Bookings essential.

Thursday 09 November 2023
6.00PM - 7.00PM
Nelson Meers Foundation Auditorium, Chau Chak Wing Museum
Book here